Edge strengthening method for composite supporting type honeycomb structure

Abstract

The invention belongs to the technical field of composite material processing, and provides a composite material supporting type honeycomb structure edge strengthening method, which comprises the following steps of: extracting characteristics of a honeycomb molded surface to be stabilized; designing and manufacturing a metal male mold matched with the honeycomb molded surface; carrying out process simulation calculation; paving, curing and post-processing the composite material frame; stabilizing a honeycomb slope; checking the honeycomb and the composite material frame; and laying an adhesive film according to a verification result, and curing and forming. The process problems of honeycomb edge slippage shrinkage, in-plane shrinkage, collapse and the like generated in the pressurizing and curing process of the high-chamfer honeycomb sandwich structure composite material part are solved, and stabilization of the high-chamfer honeycomb is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of aviation composite material manufacturing, and particularly relates to a method for reinforcing the edge of a composite material supported honeycomb structure. Background Art

[0002] In aircraft manufacturing, the proportion of composite materials has become a key metric for advanced aircraft design. Honeycomb sandwich composites, due to their advantages such as light weight, high stiffness, structural design flexibility, and excellent energy absorption, thermal and acoustic insulation, wave transmission, and corrosion resistance, have been successfully applied in the aerospace field, particularly in primary and secondary load-bearing structures in spacecraft, military, and civilian aircraft.

[0003] However, the anisotropic mechanical properties of honeycombs lead to complex and diverse failure modes. Therefore, the stabilization process of honeycombs is a key issue in the formation of honeycomb sandwich structures. Currently, the design of thick honeycomb right-angled edges (90° chamfers) is required for the nose landing gear doors of certain wide-body passenger aircraft. Conventional stabilization methods are unable to meet the stability and weight control requirements of such thick, high-chamfered honeycomb sandwich structures, which limits the design of thick honeycomb sandwich structures.

[0004] Conventional resin potting and stabilization processes are difficult to implement and are prone to defects such as bubbles and cracks. Existing resin potting materials also have high density and significant weight gain. Adhesive film stabilization and anti-slip strip tie-down processes cannot effectively protect the honeycomb sides. At the same time, in order to comply with the general trend of overall structural weight reduction in the aviation transportation field, the application of foam is also limited. Summary of the Invention

[0005] The present invention addresses the process problems of honeycomb edge slippage shrinkage, in-plane shrinkage, and collapse generated during the pressurized curing process of existing high-chamfered honeycomb sandwich structure composite material parts, and provides a composite-supported honeycomb structure edge reinforcement method. First, a composite frame matching the honeycomb profile is formed, and then it is composite-bonded with the honeycomb to form the core of the sandwich structure composite part. The composite frame can provide support for the honeycomb edge and in-plane, strengthen weak areas, and achieve stabilization of the high-chamfered honeycomb.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: A composite-supported honeycomb structure edge reinforcement method comprises the following steps: Extraction of honeycomb surface features to be stabilized; Design and manufacture of metal male molds that conform to the honeycomb surface; Process simulation calculation; Composite frame laying, curing and post-processing; Honeycomb slope stabilization; Verification of honeycomb and composite frame; Lay the film according to the verification results and solidify it into shape.

[0007] As a further solution of the present invention: the extraction of honeycomb surface features to be stabilized is specifically: extracting the required honeycomb surface size (a, b), thickness (T), chamfer (α, β) and fillet (R angle) feature information.

[0008] As a further solution of the present invention, the design and manufacture of the metal positive mold conforming to the honeycomb surface is specifically as follows: based on all characteristic information of the honeycomb to be stabilized, the metal positive mold is designed so that the surface of the metal positive mold matches the surface of the desired honeycomb.

[0009] As a further solution of the present invention: the process simulation calculation is specifically: using Abaqus finite element simulation analysis software to perform early process simulation calculation to provide a basis for the number n and combination form of composite support frame plies.

[0010] As a further solution of the present invention: the paving, curing and post-processing of the composite frame are specifically as follows: According to the simulation calculation results, n layers of prepreg are laid on the metal positive model surface; Apply a certain degree of vacuum and external pressure, increase the temperature, and solidify the composite frame in the autoclave; Trim the composite frame and remove excess material.

[0011] As a further solution of the present invention: the honeycomb slope is stabilized, specifically: Honeycomb billet preparation, cutting, shaping and drying; A layer of foam glue is applied to the side of the honeycomb, and a low vacuum is applied and the temperature is increased to solidify the foam glue.

[0012] As a further solution of the present invention, the honeycomb and composite frame are calibrated by using a calibration film for pressure calibration. After the adhesive film is covered on one side with a non-porous isolation film, the adhesive film is combined with the cured honeycomb surface and the matching composite frame, and vacuum is applied for 15 minutes.

[0013] As a further solution of the present invention: removing the vacuum and checking whether the indentations of the honeycomb core cells on the calibration membrane are uniform; If there is a shallow honeycomb indentation, or an area without a honeycomb indentation, it should be marked as a failed area. Add more film to the corresponding area and repeat the verification steps until the mark on the non-porous isolation film is complete and clear. Check the assembly for any compression, distortion or movement of the honeycomb core during the curing process. If any of these conditions occur, repeat all the previous steps.

[0014] As a further solution of the present invention: the laying of adhesive film according to the verification results and curing and forming are specifically as follows: removing the non-porous isolation film, gluing the honeycomb with stabilized slope to the composite frame with adhesive film according to the verification results, pressurizing and heating, and sending into the autoclave for curing and forming.

[0015] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: 1. This application first solidifies and forms a composite frame that matches the honeycomb profile, and then bonds it to the honeycomb composite to provide support for the honeycomb edges and in-plane, strengthening weak areas. This method is simple to operate, has a shorter cycle, can further reduce the weight of the part, and solve the stability problem of high-chamfered honeycombs.

[0016] 2. The high chamfered honeycomb reinforcement method of the present application solves the problem of honeycomb collapse, deformation, and shrinkage during the preparation process of a thick honeycomb sandwich structure with a 90° chamfer, thereby improving the preparation process level of the thick honeycomb sandwich structure and having great practical application value.

[0017] 3. This application has certain application value in the field of aviation manufacturing technology and has certain economic benefits.

[0018] 4. This application uses a cured composite frame to support the honeycomb edge, thereby enhancing the lateral pressure strength of the honeycomb and being able to resist lateral pressure under high temperature conditions during the formation of the sandwich structure. It has high application value for expanding the use size range of honeycomb sandwich structures and the development of composite material technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Schematic diagram of a process for strengthening the edge of a composite-supported honeycomb structure according to the present invention; Figure 2 A schematic diagram of a process route for a composite-supported honeycomb structure edge reinforcement method according to the present invention; Figure 3 A schematic diagram of a honeycomb surface according to a first embodiment of the present invention; Figure 4 This is a schematic diagram of the composite frame molding according to the first embodiment of the present invention; Figure 5 This is a schematic diagram of the honeycomb structure forming of the first embodiment of the present invention; Figure 6 A schematic diagram of a honeycomb surface according to a second embodiment; Figure 7 A schematic diagram of a metal male mold according to a second embodiment; Figure 8 Schematic diagram of finite element simulation analysis of different types of composite frames according to the second embodiment; Figure 9 This is a schematic diagram of the composite frame molding of the second embodiment; Figure 10 A schematic diagram of honeycomb slope stabilization according to the second embodiment; Figure 11 This is a schematic diagram of the honeycomb and composite support frame verification of the second embodiment; Figure 12 This is a schematic diagram of the honeycomb structure forming of the second embodiment. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solutions and advantages of the present invention more clear, the technical solutions in the embodiments of the present invention will be described in more detail below with reference to the accompanying drawings in the embodiments of the present invention.

[0021] In the drawings, the same or similar reference numerals throughout the drawings represent the same or similar elements or elements having the same or similar functions. The described embodiments are only some of the embodiments of the present invention, but not all of the embodiments.

[0022] The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort shall fall within the scope of protection of the present invention.

[0023] The following is combined with Figure 1-12 The embodiments of the present invention are described in detail.

[0024] Example 1 The present invention discloses a method for strengthening the edge of a composite-supported honeycomb structure, which comprises the following steps: Extraction of honeycomb surface features to be stabilized; Design and manufacture of metal male molds that conform to the honeycomb surface; Process simulation calculation; Composite frame laying, curing and post-processing; Honeycomb slope stabilization; Verification of honeycomb and composite frame; Lay the film according to the verification results and solidify it into shape.

[0025] Preferably, the honeycomb profile feature extraction to be stabilized specifically includes extracting the required honeycomb profile dimensions (a, b), thickness (T), chamfers (α, β), and fillet (R angle). In this embodiment, honeycombs having at least one chamfer of 90° are targeted.

[0026] Preferably, the design and manufacture of the metal positive mold conforming to the honeycomb profile is specifically as follows: based on all characteristic information of the honeycomb to be stabilized, the metal positive mold is designed so that the profile of the metal positive mold matches the profile of the desired honeycomb.

[0027] Preferably, the process simulation calculation is specifically: using Abaqus finite element simulation analysis software to perform preliminary process simulation calculation to provide a basis for the number n of composite support frame plies and the combination form (semi-enclosed, fully enclosed).

[0028] Preferably, the paving, curing and post-processing of the composite frame are specifically as follows: According to the simulation calculation results, n layers of prepreg are laid on the metal positive model surface; Apply a certain degree of vacuum and external pressure, increase the temperature, and solidify the composite frame in the autoclave; Trim the composite frame and remove excess material.

[0029] Preferably, the honeycomb slope is stabilized, specifically: Honeycomb billet preparation, cutting, shaping and drying; A layer of foam glue is applied to the side of the honeycomb, and a low vacuum is applied and the temperature is increased to solidify the foam glue.

[0030] Preferably, the honeycomb and the composite frame are checked, specifically as follows: to avoid defects such as debonding and air holes caused by poor cooperation between the composite frame and the honeycomb and to ensure the bonding quality of the honeycomb and the composite plate, a pressure check is performed using a check film. After the film is covered with a non-porous isolation film on one side, the film is combined with the cured honeycomb surface and the matching composite frame, and vacuum is applied for 15 minutes.

[0031] Preferably, the vacuum is removed and the indentations of the honeycomb core cells on the calibration membrane are checked to see whether they are uniform; If there is a shallow honeycomb indentation, or an area without a honeycomb indentation, it should be marked as a failed area. Add more film to the corresponding area and repeat the verification steps until the mark on the non-porous isolation film is complete and clear. Check the assembly for any compression, distortion or movement of the honeycomb core during the curing process. If any of these conditions occur, repeat all the previous steps.

[0032] Preferably, the step of laying the adhesive film and curing the film according to the verification results is as follows: removing the non-porous isolation film, gluing the honeycomb with stabilized slope to the composite frame using the adhesive film according to the verification results, pressurizing and heating the honeycomb, and sending the honeycomb into an autoclave for curing and forming.

[0033] Example 2 The specific manufacturing process of composite frame support reinforcement for honeycomb with a thickness of 70mm and a maximum chamfer of 90° is as follows: Step 1: First, extract the required honeycomb surface. The dimensions include size, thickness, chamfers, and other characteristic information. The honeycomb is 70mm thick, and the four sides have chamfers of 90°, 75°, 75°, and 65°. Process the honeycomb according to this information.

[0034] Step 2: Design the metal male mold and the tooling surface design as follows Figure 7shown.

[0035] Step 3: Simulation calculation: Use Abaqus finite element simulation analysis software to conduct early process simulation and provide suggestions for composite frame layup and combination. Figure 8 Finite element simulation analysis software is used to study the deformation of composite frames with different combinations and different layer thicknesses under an external pressure of 0.3 MPa (the honeycomb is hidden in the figure).

[0036] The simulation results show that the maximum deformation occurs at the bottom of the right-angle edge. The two layup schemes exhibit essentially the same deformation under a fixed external pressure, and the ply thickness has little effect on the maximum deformation. A three-ply layup was selected, with a fully enclosed configuration.

[0037] Step 4: Lay 3 layers of prepreg on the upper surface of the metal positive mold in a fully enclosed manner.

[0038] Step 5: Apply a constant temperature of 180℃±6℃ for 120 minutes, a vacuum of 0.027~0.034MPa, and an external pressure of 310KPa to solidify the composite support frame.

[0039] Step 6: Stabilize the honeycomb slope. Apply a layer of foam glue to the sides of the honeycomb, apply a low vacuum, and heat up to cure the foam glue. The foam glue filling process is as follows: evacuate to -0.025MPa at room temperature, hold at 60°C for 15 minutes, then continue heating to 107-116°C and hold for 90 minutes. Set the air temperature rise / fall rate at 1.5°C / min, and cool to below 60°C to complete the curing.

[0040] Step 7: Verify the honeycomb and composite support frame. Use a calibration film to perform pressure verification. After covering one side of the adhesive film with a non-porous isolation film, place the composite frame over the honeycomb. Vacuum to above 0.06 MPa at room temperature and maintain the vacuum for 15 minutes.

[0041] Step 8: Remove the vacuum and inspect the membrane for uniform indentations of the honeycomb core. Areas with shallow or no honeycomb indentations should be marked. Check the assembly for any compression, distortion, or movement of the honeycomb core during the curing process. If not, add more adhesive film to the appropriate areas and repeat step 7 until the non-porous barrier membrane has a clear, complete indentation.

[0042] Step 9: Remove the non-porous isolation film and use adhesive film to bond the honeycomb with the stabilized slope to the composite frame. The curing process is as follows: maintain a constant temperature of 180°C ± 6°C for 60 minutes, evacuate the room temperature to 65 kPa to 75 kPa and maintain the vacuum until the curing is complete. The air heating rate is set at 1.2°C / min from room temperature to 120°C, and 0.8°C / min from 120°C to 180°C. The air cooling rate is set at 1°C / min. Cool the temperature to below 60°C to complete the curing. This results in a stabilized honeycomb core.

[0043] So far, the purpose of the present invention has been achieved.

[0044] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for strengthening the edge of a composite-supported honeycomb structure, characterized in that: The following steps are involved: Extraction of honeycomb surface features to be stabilized; Design and manufacture of metal male molds that conform to the honeycomb surface; Process simulation calculation; Composite frame laying, curing and post-processing; Honeycomb slope stabilization; Verification of honeycomb and composite frame; Lay the film according to the verification results and solidify it into shape.

2. The method for strengthening the edge of a composite-supported honeycomb structure according to claim 1, wherein: The extraction of honeycomb surface features to be stabilized specifically includes extracting required honeycomb surface dimensions (a, b), thickness (T), chamfers (α, β) and fillet (R angle) feature information.

3. The method for strengthening the edge of a composite-supported honeycomb structure according to claim 1, wherein: The design and manufacture of the metal positive mold conforming to the honeycomb profile is specifically as follows: based on all characteristic information of the honeycomb to be stabilized, the metal positive mold is designed so that the profile of the metal positive mold matches the profile of the desired honeycomb.

4. The method for strengthening the edge of a composite-supported honeycomb structure according to claim 1, wherein: The process simulation calculation specifically includes: using Abaqus finite element simulation analysis software to perform preliminary process simulation calculation to provide a basis for the number n and combination form of composite support frame plies.

5. The method for strengthening the edge of a composite-supported honeycomb structure according to claim 1, wherein: The composite frame paving, curing and post-processing are specifically as follows: According to the simulation calculation results, n layers of prepreg are laid on the metal positive model surface; Apply a certain degree of vacuum and external pressure, increase the temperature, and solidify the composite frame in the autoclave; Trim the composite frame and remove excess material.

6. The method for strengthening the edge of a composite-supported honeycomb structure according to claim 1, wherein: The honeycomb slope stabilization is specifically as follows: Honeycomb billet preparation, cutting, shaping and drying; A layer of foam glue is applied to the side of the honeycomb, and a low vacuum is applied and the temperature is increased to solidify the foam glue.

7. The method for strengthening the edge of a composite-supported honeycomb structure according to claim 1, wherein: The honeycomb and composite frame calibration is specifically as follows: pressure calibration is performed using a calibration film, after the adhesive film is covered on one side with a non-porous isolation film, the adhesive film is combined with the cured honeycomb surface and the matching composite frame, and vacuum is applied for 15 minutes.

8. The method for strengthening the edge of a composite-supported honeycomb structure according to claim 7, characterized in that: Remove the vacuum and check whether the indentations of the honeycomb core on the calibration membrane are uniform; If there is a shallow honeycomb indentation, or an area without a honeycomb indentation, it should be marked as a failed area. Add more film to the corresponding area and repeat the verification steps until the mark on the non-porous isolation film is complete and clear. Check the assembly for any compression, distortion or movement of the honeycomb core during the curing process. If any of these conditions occur, repeat all the previous steps.

9. The method for strengthening the edge of a composite-supported honeycomb structure according to claim 1, wherein: The method of laying the adhesive film and curing the film according to the verification results is as follows: removing the non-porous isolation film, gluing the honeycomb with the stabilized slope to the composite frame using the adhesive film according to the verification results, pressurizing and heating the honeycomb, and sending the honeycomb into the autoclave for curing and forming.

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